Who edited my text file?

I was editing my text file in gvim & I was getting message that its changed & to load again.
I work in a workplace environment with everyone having there username..
How can I know that who edited my file?

to protect your text file, set the permisson as 600

6 - read & write for you

actually I havent found my answer yet.
is there any editing log?

No there is no editing log.

even after changing the permission, if u face this problem, then i guess it should be some program ( process ) which is running in your username is editing that log file !